SIAZATLAN TTNIVALYES 507 



stones near low vrater mark, rare ; C. B. Adams. — Mazatlan ; 

 very rare ; L'pool Col. 



Tablet 2419 contains 3 sp. narrow.— 2420, 3 do. broader.— 

 2421, 2 sp. one with operculum, tbe otker after the acid process. 



646, (I.) Anachis (Pcostellata, var.) pachydeema. 



A. t. "A. costellatce" similUma, sedplerumque latiore, fusco- 

 purpurea, alhido fasciatd et in tuberculis maeulatd ; epidermide 

 solida, rugis incrementi confertis ornata, haud valde adhcerente ; 

 operculo elongato, subarcuato, scahriusculo, apice terminali 

 scspe decollato. 



Comp. Columbella varia. Sow. va. Proc. Zool. Sac. 1832, p. 116. — 

 3im. Syn. Nov. Test. Viv. p. SQ.—Sow. Thes. Conch, p. 130, 

 no. 54, pi. 39, f. 116-7. — Desh. in Lam. An. s. Vert. vol. x. 

 p. 282, no. 31.— C. B. Ad. Ban. Shells, p. 100, no. 105.— 

 = (Columbella) Anachis varia, S. Sf A. Ad. Gen. i. 184. 



It might be thought that the true A. costellata is this shell 

 with the outer part of the epidermis rubbed off ; but in this 

 form, when the epidennis comes off, it leaves the dark purplish 

 brown surface of the shell itself, not the close thin skin of the 

 chesnut-stained A. costellata. These shells were regarded by 

 an eminent authority as one of the many varieties of A. varia.* 

 They appear however much more nearly related to A. costel- 

 lata, from which the operculum does not perceptibly differ. 

 This shell, like A. costellata, is more or less turrited, sometimes 

 obese ; with ribs more or less numerous, more or less waved, 

 more or less produced towards the base ; interstices more or 

 less cancellated by spiral striae. The flattening of the middle 

 of the lip often gives the ribs the appearance of being sHghtly 

 tubercular both above and below. Colour purple brown, 

 more or less dark and spotted or banded with white. The 

 best character is the epidermis, which is thick, lying in trans- 

 verse layers as in C. major, but coarser in proportion, dark 

 green. A broad sp. measures long. '66, long. spir. '34, lat. '32, 

 div. 40". 



Hah. — Mazatlan ; rare ; L'pool Col. 



Tablet 2^122 contains 6 sp. in different stages. — 2423, 1 sp. 

 with operculum in situ, and one separate operculum. 



• The Col. terpsichore of Menle may belong to this species, though his 

 diagnosis appears to apply better to C, coronata. 



